Large computer, storage, or networking server systems used in datacenters usually consist of a fairly large number of power rails. When a circuit board is powered up, powered off, or going into different power states (such as fault or throttled), all of these rails need to be powered up/down in a specific order for the chips and active components on the board to be functional, or to behave (such as turn on/off, sleep) corresponding to the definition of the power state. This process is called power sequencing which is typically performed by a dedicated component on-board called a sequencer. Typical simpler boards will have one sequencer with pre-programmed firmware that contains the order and delay information which controls the sequencing of all power rails. When the number of power rails become large, more of such devices are needed and they take precious board space, add design complexity, and become hard to manage. In some cases, a “master-slave” configuration of multiple sequencers need to be maintained, further complicating the board level design.
The circuits that are power sequenced include a silicon interposer below the silicon die and above the package substrate for an electrical interface routing between one socket or connection to another. The purpose of an interposer is to spread a connection to a wider pitch or to reroute a connection to a different connection.